Electric relay and motor for use therein



J. S. HOL LJDAY. ELECTRIC RELAY AND MOTOR FOR use THEREIN.

APPLICATION FILED JULY 31. I916- .Putvnfvd July 22, 1919.

WITN ESSF'? 25 bodying my invention.

diagram showing for one frequency the cur- 50 signal UNITED STATES PATENT OFFICE JOHN S. HOLLIDAY, OFWILKINSBURG, PENNSYLVANIA. ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

ELECTRIC RELAY AND MOTOR FOR. USE THEREIN.

Application filed July 31, 1916.

new and useful Improvements in Electric Relays .and Motors for Use Therein, of which the following is a specification.

My invention relates to electric relays and motors for use therein.

One object of my invention is to provide a relay immune to current of a predetermined frequency. Other objects of my invention will appear in the following description.

I shall describe one form of relay embodying my invention, andalso one way of using the same in a railway signaling system, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figure 1 i -is a diagrammatic view showing one form and arrangement of railway signaling circuits comprising one form of relay R em- Fig. 2 'is a vector rents in the various members of relay B. Fig. 3 is a similar vector diagram for current of said predetermined frequency, Fig. 4;

is a diagrammatic view showing the electrically equivalent circuit for relay R.

Similar reference characters refer to simi lar parts in each of the views.

Referring first to Fig. 1, reference characters 4 and 5 designate the track rails of an electric railway, which rails are divided into i sections by insulated joints 2. In the draw- I ing I have shown only one section XY and the beginning and end respectively of the two adjoining sections. For the control of trafiic through section XY, I provide a signal S having a semaphore arm 20, which, when in the vertical position, as shown, in-

dicates proceed, andwhich, .when in the horizontal position, indicates stop. These positions of the signal arm are controlled by a relay R, through the following circuit: from a battery E, through contact finger 6 of relay R, wire 8, operating mechanism of terry;

clay R operates on the induction prmciple and comprises a movable member 10 for operating contact point 6 which member Specification of Letters Patent.

S (not shown) and wire 7 to bat- Patented July 22, 1919.

Serial No. 112,222.

is responsive to currents in windings 11 and 12, provided the current in one winding is sufliciently displaced in phase from the current in the other. Relays of this type are well known in the art and need no further explanations. \Vindings l1 and 12 are connected in series and derive their current from a track circuit which comprises the track rails 4 and 5, a source of signaling current connected to these rails adjacent one end of section X'Y, and the windings 11 and 12' connected to these rails adjacent the other end of the section. As here shown, the source of signaling current is a transformer M, the primary of which receives signaling current from an alternator H through a transmission line N. The signaling current flows from the transformer M through the track rails to windings 11 and 12 in series.

For producing a difference in phase of the current in winding 12 relative to the current in winding 11, I provide a shunt around winding 11, which shunt comprises an open core transformer T the primary of which is connected in parallel with winding 11 and to the secondary of which is connected a condenser 30. Referring now to the vector diagram Fig. 2, vector OE represents the voltage impressed on winding 11. For purposes of this vector diagram, the shunt circuit around winding 11 may be considered, as shown in Fig. 4:, as a parallel connection of the condenser 30 and an inductance T said inductance having such characteristics that the current taken thereby is the same as the magnetizing current of the transformer T. The current in winding 11, shown by vector OA, is' in phase with the voltage OE because the winding 11 is made with a substantially unity power factor. Because of its open magnetic circuit, the current in inductance T or the exciting current of the transformer, is rather large and lags considerably 'behind the phase of voltage OE, as shown by vector AC. The current taken by the condenser 30 is of sub stantially zero power factor and leads the voltage by approximately ninety degrees, as shown by vector GB. The current in winding 12 is evidently the vector sum of the three currents above-mentioned, and is represented by the vector OB. It is apparent that the current in winding 12 is displaced tion X-Y.

in phase from the component thereof in winding 11 by a Considerable angle in counterclockwise direction. The rotor 10 of the relay R responds to these currents by operating contact finger 6 intoengagement with its contact point so that the semaphore 20 of signal S is raised to the vertical po s1 tion and indicates proceed.

When a vehicle V enters the track sectio XY, the wheels and axles thereof form a path of low resistance between the rails 4 and 5 so that the current in the relay wlndin'gs is reduced to an amount insuflicient. hold contact finger 6 against its contact points. The contact, therefore, opens'and 1 breaks the circuit for signal S, so'that the? semaphore 20 of the signal drops to the ho'rizontal position and indicates stopi Thus it appears that relay R is IGSPODSIVB tO the signaling current in the track circuit of sec-" tion XY and controls the signal S to ind1--v cate proceed or ,stop according to the presence or absence of vehicles in sec- Propulsion current for the operation of the cars or trains along the railway is furnished by an alternator G, one terminal of which is connected to a trolley wire or third rail L, and the other terminal of which is grounded to the track'railsg This current differs in frequency from the signaling current, the usual frequency of the propulsion current being 25' cycles and that of. thesig naling current 60 cycles. The propulsion current flows from one terminal of the generator through wire L, vehicle V, track rails 4 and 5in parallel to the other terminal of the generator G. Impedance bonds I are provided for passing the ropulsion current around the insulated jolnts without interfering with the flow of the signaling current as'well understood in the art.

- drives the propulsion motors-which relay R is s which for convenience s chosen equal to a In flowing through the vehicletlie current I have not shown on the drawing. 'j 5 For avariety of causes, to mention j'only unequal bonding-of the track rails, it may happen that for the propulsion current the potential of one' track rail in section XY is higher than the potential of theother rail, so that a partof the propulsion current flows from one track rail .to the "other, through, the windings 11 and 12 offrelay R. g

The 25 c cle voltage'in winding 11 0 liown in Fig 3 by vector 0- E,

the voltage OE in Fig. 2. The current in winding 11 resulting from this voltage is shown by vector 0A. The current in inductance T or the exciting current of transformer T, represented by a vector A'C', is considerably larger than the exciting current of the transformer at 60 cycles, approximately in'the ratio of 60 to 25. On

the other hand, the current for condenser 30, represented by vector CB, is decreased in substantially the same ratio. The phase I of the resultant current O'B in Winding 12, is approximately the same as the phase of the current 0A in winding 11, preferably differing therefrom by a small angle in clockwise direction. This causes a slight torque in clockwise direction" on member 10, which torque tends to assist gravity in opening the relay contact and is therefore on the safe side. The relay is therefore immune to the propulsion current, in that the presence of this current in the relay windings cannot cause the signal S to give a clear or. proceed indication. It will be seen,

-,therefore, that whenthe section X-Y is occupied by a car or train, even if there should be a considerable difference of potenof the propulsion current across the terminals of relay -R this relay would not be operated thereby to close its contact 6, and in factthe presence of the propulsion current-would tend to assist gravity in holding this contact open. a

' Moreover, even if the arrangement of the apparatus shown in Fig. l is disturbed, the propulsion current cannot cause the relay to close its contact because the current in winding 12 cannot under any circumstances differ in phase from the current in winding 11 b a'counterclockwise angle. F or-example,

i transformer T should become disconnected from'winding 11, the propulsion current would be of'the same phase in both windings. Again, if'the condenser should become'disconnected from transformer T the 25 cycle current in winding 12 would be represented in FigB- by a vector O'C'. This current, being at} a clockwise angle to the current in winding 11, would tend to open the relay'contact; If several turns of the primary of transformer T should become short-circuite'd, as5 indicated on the drawing by a dottedjcohnection 31, or if several turns of the'isecondary winding of this transformer-should become short-circuited as indicated by dotted connection 32, the current flowing in; these connectipns would be represented. by aj'vector B D, and the resultant current infw inding 12, shown by a vector OD, would also be unable to "effect a closureof the contact "of the relay.

Thus it appears thatflany 'clerangement of the apparatus causes 'alfailure on the side of safety, it being impossible for the propulsion current to'close contact .6 and thus a cause a proceed indication of the signal.

Although ,I. have herein shown and described only one form of relay embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention. Havin thus described my invention, what I claim is:

l. A relay comprising two windings connected in series, in which windings a plurality of currents difl'eringin frequency may flow at different times, means shunted across one of said windings for affecting the phases of said,currents in the other winding, said means comprising an open core transformer and a condenser connected to the secondary thereof, a member responsive to currents displaced in phase in said windings and a contact governed by said member.

2. A motor immune to current of a predetermined frequency comprising two windings connected in series, a transformer having a high magnetizing current connected across one of said windings, a condenserconnected to the secondary of sald. transformer, said condenser and transformer being "so proportioned that for current of a predetermined frequencythe current in the second winding is substantially in phase with the current in the first winding, and a movable member responsive only to currents in said windings displaced in phase.

3. A motor immune to current of a predetermined frequency comprising two windin'gs, an open core transformer whose primary is connected across one of said windings, a condenser connected in circuit with the secondary of said transformer, sald conmember responsive only to currents in said windings displaced in phase.

4. A relay comprising two windings connectedin series, a transformer comprising av magnetic core having an air gap therein,

the primary winding of said transformer being connected in parallel with one of said relay windings, a condenser connected in circuit with the secondary of said transformer, a movable member responsive to currents in said relay windings when said currents are displaced in phase, and a contact controlled by said member.

5. An alternating current motor comprising two windings connected in series, a' transformer Whose primary is connected across one of said windings, a condenser connected in circuit with the secondary of said transformer, and a movable member responsive to currents in said windings displaced in phase.

In testimony whereof I affix my signature in presence of two witnesses.

. JOHN s. HOLLIDAY. Witnesses A. C. Noun, 0. H. Zmnn'r. 

